Help troubleshooting old radio

Discussion in 'The Projects Forum' started by bob808, Oct 20, 2010.

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  1. bob808

    Thread Starter New Member

    Oct 20, 2010
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    Hello all. I just got an old radio from a flea market but I couldn't manage to get it in working condition. I opened it and saw 2 connectors witch looked like the ones from a square 9V battery. The thing is that the negative lead doesn't actually fit in the battery, it's a bit larger, and even if i touch it on the battery I can only hear some crackling buzz in the speaker for a fraction of a second and nothing happens. I attached some pictures, maybe you guys can tell me the voltage necessary for this radio, as well the model if you know it
    Thank you
     
  2. Kermit2

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    Feb 5, 2010
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  3. Bernard

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    Aug 7, 2008
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    Old battery sounds like an Everyready 226 9V with connections on each end. I cut off connectors and replaced with newer 9V connector on a Realistic 8 transistor radio, mid 1960s, still works.
     
  4. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    Two things come to mind with an old radio like that.

    First. It may not be a 9V battery. I had some batteries for an old multimeter a few years ago and they were 22V. They looked the same with a connector on each end. You will have to find out exactly what the voltage is.

    Second. Being old I would sugest you replace ALL electrolytic capacitors with new ones. I had an old car radio from a 1962 Pontiac and it wouldn't work. I started replacing the caps and it slowly got better so I just replaced them all. Worked perfectly.
     
  5. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Can you identify any transistors in it --they may be metal tubes? How old is it (pre-1960's or later)? Brand name?

    BTW, it's 22.5V, not 22V for the old batteries. I am pretty sure the 1/2 volt won't matter, but using those old batteries brought back fond memories.

    John
     
  6. debe

    Well-Known Member

    Sep 21, 2010
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    Hi Bob, definitley 9V battery & the radio is using Philips modules, the sealed one is front end/ IF module the other is audio amp module. They were either all metal transistors or a mix of plastic & metal. Daryl
     
  7. marshallf3

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    Jul 26, 2010
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    The voltage ratings on the electrolytics will give away what voltage it was designed to run on, in those days they rarely went much above the supply voltage in rating.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Very nice find there, mate.

    I love the wood. Too bad someone replaced the right knob with a white plastic one. I have some very nifty aluminium knobs that would look just great on it, but shipping costs to The Land Downunder would be absurd.

    You have some corrosion problems going on, just from the look of the gang capacitor (the thing with all the half-round metal plates) and the battery connectors. Bad electrolytic capacitors would be my first target. After a number of years, the electrolyte in the caps eats them from the inside out. Look for any signs of leakage, or bulging. If you're serious about preserving it, replacing any/all electrolytics with modern fresh ones would be the first order of the day.

    In a radio that old, it's important to first document everything - even before you try cleaning it. Just the act of cleaning it can remove all-important markings, causing you to eventually relegate it to the dustbin, which would be a real shame.
     
  9. bob808

    Thread Starter New Member

    Oct 20, 2010
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    Hey guys, thank you for the warm welcome and all of your answers. I found some time to do a bit of work on the radio. I managed to check out the caps. I attached a picture and noted them like this:

    1. - 125uF - 10V
    2. - 200uF - 6.4V
    3. - 200uF (i guess, hard to see) - 6.4V
    4. - 22000pF - 100V
    5. - 5600pF - 400V
    6. - 10uF - 16V
    7. - ceramic capacitor 200MF (?) - 12V
    8,9,10 - they got 3 pin connection and 2 color spots, one orange on top and one red on side. don't know what they are.
    11,12 - same, don't know what they are.

    So I'm guessing it was a 6V input. I must have damaged something with that 9V battery. Probably the caps were already dead so no damage done. I attached a picture of a coil end half being riped away from the solder joint. I presume I must reattach it.
    I will try to find a replacement for all the caps just to be sure. I will let you know when I'm finished. Thank you once again and wish you a great day!

    p.s.
    @ SgtWookie
    can you pm me with a picture of those knobs? :) I might be willing to pay for the whole thing
     
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  10. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    I am not saying this is a problem but it looks like the begining of one. If you compare the two caps in picture 1, caps 1 and 2, you will notice that the blue insulation on cap 2 covers the end more than it does on cap one. As these are 2 different value caps and it may just be a manufacturing process but this is the type of thing you should look for in older electronics. If this was the problem it would indicate that the one with less blue insulation on it has expanded and is squeezing out of it.

    Also looking at the cleanliness of the insides and the look of some of those caps it doesn't really look that old. I would say maybe 70's vintage? I could be wrong.
     
  11. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The numbers 8,9,10 and 11 (the three pin parts) are transistors.
    When you look at number 11 you see the code AC12 (or something like that) on it.
    It is a germanium transistor.
    Perhaps you can read the codes better.

    What is the brand and type of the radio?

    Bertus
     
    Last edited: Oct 21, 2010
  12. bob808

    Thread Starter New Member

    Oct 20, 2010
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    I wish I'd new the brand name. The top part from the band selectors is missing and I want to see an original to try to duplicate. Doesn't seem that old, but it sure is at least 70's. I managed to get it working, it's 6V input. I only found 1 local station, but the music is really nice :cool: so after a bit cleaning I'll stick with it. I get a bit static on the background thou. What can I do to improve the number of received stations and the quality? Shall I take out and clean the band seeker? I don't know the exact name in English (the mechanism behind the knob). All the coils seem to be OK.
    I must mention that I'm a DIY guy :D and I know a bit electronics. But this is my first radio that I troubleshoot and for the moment I'm really happy with the one station I receive. It's on MW band, I also got LW and SW. Dunno if anyone is still broadcasting anything on those frequencies here. I'll have a look tomorrow and see what I can find out.
    Thank you very much for your help and any tips to improve quality is welcome.
     
  13. bob808

    Thread Starter New Member

    Oct 20, 2010
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    number 11 has AC|12 257 written on it.

    later edit

    I found the old batteries for the connectors that look just like the ones on a new 9V one. I attached a picture below
     
    Last edited: Oct 21, 2010
  14. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    WOW. Where did you get that photo of the batteries?????? I have been looking for the battery in the top left hand corner for years. Do you know if they are still available? I have an old WW2 mine detector (metal detector) that needs a 90V battery.
     
  15. bob808

    Thread Starter New Member

    Oct 20, 2010
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    I got it from this site:
    http://www.antiqueradio.org/bsupply.htm
    and as well you can buy some of those batteries from this site:

    http://www.tubesandmore.com/

    I just saw that they got 45V batteries so it won't be hard :)
     
  16. SgtWookie

    Expert

    Jul 17, 2007
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    No need to PM, mate.

    Here's a link to the item on Radio Shack's site:
    http://www.radioshack.com/product/index.jsp?productId=2102832
    Except what they show in the photo looks a tad cheesier than the ones I have.

    It will be difficult to get a good photo of them with the equipment that I have available. I'll try to post up a photo in the next day or so - but first, these knobs were designed for 1/4" shafts (yes, good old English measurement units, or if you prefer, 0.250", or 6.35mm shafts, and they have one brass setscrew.

    I just pulled one out of the "treasure bins" to measure. It's 24.4mm/0.96" in diameter, 15mm/0.59"long. The face looks just like the image on the Radio Shack site. The outside radius is knurled aluminum; but it is a straight knurl (parallel and perpendicular to the Z-axis of the bore). The shaft hole is about 0.480" deep. The center of the brass setscrew is approximately 0.250" from the bottom. Unless you had at least an 0.3" shaft length sticking out, it would not work. If the shaft has a cut in it (to make it spring-tension) you might be able to shim it to use these knobs.

    But, let's get it working first - and worry about the asthetics later. First, document what you have as completely as possible.

    You say that the transistors have colored markings on them. The colors AND their placement on the transistor is critical knowledge. It will take some research, but generally in the old days, a tab was placed on the transistor housing to mark the position of the emitter lead. The radio you have appears to pre-date the TO-18/TO-39 case transistors. It's even likely that the transistors are all germanium PNP, as in the early days, PNP was what was available.
     
  17. debe

    Well-Known Member

    Sep 21, 2010
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    Posted pic of a common Germanium type transistor AC128 as used in audio modules generaly with AC127 which is NPN Germanium Vcb max 32v & Ic max 500Ma as a pair. There was usually a small disc NTC thermistor in the circuit to stabilise the output pair. Daryl
     
  18. n1ist

    Active Member

    Mar 8, 2009
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    Item 7 is likely a 200uF 12V tantalum capacitor. You occasionally see mF (or even MF for those who don't care about the difference between micro- and mega-) instead of uF. Likewise, old schematics often have uuF instead of pF.
    /mike
     
  19. SgtWookie

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    Jul 17, 2007
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  20. bob808

    Thread Starter New Member

    Oct 20, 2010
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    The ones on Radioshack looks almost identical to the original one. I measured it and it's 30mm in diameter and 8mm thick. The shaft is kinda short, less then .3 inches. Anyway radioshack doesn't ship to Romania. Can you find out the shipping cost from Australia?
     
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